Method of manufacturing polishing pad

ABSTRACT

A method of manufacturing a polishing pad is described. A mold having a mold cavity therein is provided. At least a strip is buried in the mold. A polymer foam material is injected into the mold cavity of the mold. The polymer foam material is cured to mold the polymer foam material into a molding polymer article. A mold release process is performed to obtain the molding polymer article. The strip on the molding article is removed to form a polishing pad having at least one groove thereon.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of a prior application Ser. No.10/438,406, filed on May 14, 2003, now U.S. Pat. No. 7,132,070 whichclaims the priority benefit of Taiwan application serial no. 91133682,filed on Nov. 19, 2002. All disclosures are incorporated herewith byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing a polishingpad. More particularly, the present invention relates to a method ofmanufacturing a polishing pad having grooves thereon.

2. Background of the Invention

In an integrated circuit fabrication, Chemical Mechanical Polishing(CMP) is one of the most important global planarization techniques toremove minute unevenness on a wafer surface to achieve planarization.The technique uses of a grinder-like mechanical polishing theory, sothat an uneven surface profile of a wafer can be planarized when anappropriate reagent is used. During a polishing process, the polishingpad moves on the wafer, and the abrasive particles of the reagentpressed by the polishing pad contact with and slide on the wafer, sothat the wafer is polished due to the friction between the wafer and theabrasive particles. The softness, the hardness, and the roughness of thephysical property of the polishing pad have an effect on the interactionbetween the abrasive particles in the slurry, so that the interactionbecomes irregular in the horizontal direction and the verticaldirection. Under a prescribed pressure, a force in the horizontaldirection is one of the important factors, which decides the quality ofthe planarization. The polishing pad must sustain the press of thepolishing head of the wafer to maintain the planarization. In addition,the distribution of the abrasive particles in the slurry is veryimportant to the uniformity of the polished surface of the wafer.Accordingly, the polishing pad must have enough hardness to provide thepolishing function and have enough cells to hold the slurry.

The polishing pad further has grooves formed thereon. The groovesprovide a roughness surface to benefit polishing and advantage theuniformity of the slurry distribution. The larger grooves can promotethe fine particles in the slurry to disperse uniformly and can hold muchof the removal residue and inactive slurry. However, the polishingpresses cannot maintain coincidence if the grooves too large.Accordingly, the planarization of the polished surface is lower.

A method of manufacturing polishing pad in the prior art has beendisclosed. A polymer material is injected into a mold. After the polymeris cured and molded, a mold release process is performed to obtain amolding article. Afterwards, the molding article is cut by a lathe or amachining center to form the desired feature of grooves.

In addition, U.S. Pat. Nos. 4,841,680 and 6,095,902 of Rodel Inc.disclose methods of manufacturing polishing pad. The former describes aporomeric polishing pad formed on a first substrate is formed usingsolvent/non-solvent polymer coagulation technology and high temperatureto evaporate the residue solvent. Thereafter, a second substrate isaffixed to the top of the poromeric layer, and the first substrate andthe poromeric base layer are removed using a blade or a rotatingabrasive cylinder to expose and open the underlying cell. The latterdescribes that the solid ingredients are mixed, melted, and reacted in amold to form a cake. The cake is then sliced or cut to form polishinglayers and then the polishing layer is affixed to a backing orsupporting layer to form a polishing pad.

However, in the above methods, the steps of polishing the pad comprisemolding, removing the manufacturing substrate/cutting to form layers andbonding. Accordingly, the process requires much time and work. Inaddition, the processes of removing the manufacturing substrate/cuttingto form layers are difficult to control. Therefore, the size of thecells are not uniform, the surface cells are smaller, the opening wallsof the working surface increase, and the diameter of surface cell issmaller than the diameter of the underlying cell. Accordingly, thepolishing stability is low.

On the other hand, Taiwan Patent Appl. No. 90,123,032 of Rodel Inc inU.S.A. discloses a method of manufacturing a polishing pad having amicro-texture thereon. The micro-texture was created by utilizing anIkegai, Model AX4ON lathe and a lathe bit made from high-speed toolsteel mounted in a standard bit holder. The tool was applied to the padsurface at a cut depth of 0.013 mm and translated in one pass on alinear path across the pad surface along the equator. The speedcontroller adjusted the rotational speed of the pad to maintain aconstant tool velocity relative to the pad (in the azimuthal direction)of 6 meters/min. Cutting debris was removed using a 3.5 HP SearsCraftsman Wet/Dry Vacuum. However, the grooves on the polishing pad areformed by means of cutting, so that the sharp and the linear velocity ofthe blade, the temperature and the humidity of the atmosphere are notfixed. Accordingly, the numbers of the macro defects formed on thepolishing pad are different, and the performances of each polishing padhave a large difference.

SUMMARY OF THE INVENTION

The present invention provides a method of manufacturing a polishing padto solve the stability issue of the polishing pad in the prior art.

The present invention provides a method of manufacturing polishing padto solve the problem of the difference of performance of each polishingpad because of the difference of the number of the macro defects in theprior art.

The present invention provides a method of manufacturing a polishingpad. A mold having a mold cavity therein is provided. Strips are buriedin the mold. A cross-sectional shape of the strips comprises a polygonform, an arc form or an irregular form, for example, a triangular shape,a hexagon shape, a circular shape, a square shape, a rectangular shape,a spiral shape, a tree-form or a radiative form. The strips buried inthe mold are arranged to a radiative form, a concentric circle form, agrid form, a triangle form, a spiral form, a rhombus form or aperforation form. The material of the strips comprises a polymermaterial or a metal material, wherein the polymer material comprisespolypropylene (PP), polyethylene (PE) or polytetrafluoroethylene (PTFE).A polymer foam material is injected into the mold cavity of the moldafter the strips are buried in the mold. The polymer foam material iscured and molded. Thereafter, a mold release process is performed toobtain a molding polymer article. The polymer foam material comprises apolyurea (PU) foam material. The method of manufacturing the polyureafoam material and the process condition thereof has been disclosed byApplicant in Taiwan Application number 91,117,406. The strips on themolding article are removed from the molding polymer article to form apolishing pad having grooves thereon. The pattern of the grooves aretransferred from the strips, so that the pattern of the grooves comprisea radiative form, a concentric circle form, a grid form, a triangleform, a spiral form, a rhombus form or a perforation form to improve theuniformity of the slurry distribution.

The present invention also provides a method of manufacturing apolishing pad. A mold having a mold cavity therein is provided. Stripsare buried in the mold. The cross-sectional shape of the stripscomprises a polygon form, an arc form or an irregular form, for example,a triangular shape, a hexagon shape, a circular shape, a square shape, arectangular shape, a spiral shape, a tree-form or a radiative form. Thestrips buried in the mold are arranged in a radiative form, a concentriccircle form, a grid form, a triangle form, a spiral form, a rhombus formor a perforation form. The material of the strips comprises a polymermaterial or a metal material, wherein the polymer material comprisespolypropylene, polyethylene or polytetrafluoroethylene. A first polymerfoam material such as a polyurea (PU) foam material is injected into themold cavity of the mold after the strips are buried in the mold. Thefirst polymer foam material is cured and molded. Thereafter, a secondpolymer material is injected into the mold cavity of the mold and thenthe second polymer material is cured and molded. Thereafter, a moldrelease process is performed to obtain a molding polymer article havingtwo shaped layers. The method of manufacturing the polyurea foammaterial and the process condition thereof has been disclosed byApplicant in Taiwan Application number 91,117,406. The second polymermaterial comprises a polyurea material, a silicone rubber, polybutadienerubber, poly (vinyl chloride) latex or poly (methyl methacrylate) latex.The strips on the molding article are removed from the molding polymerarticle to form a polishing pad having grooves thereon. The pattern ofthe grooves are transferred from the strips, so that the pattern of thegrooves comprises a radiative form, a concentric circle form, a gridform, a triangle form, a spiral form, a rhombus form or a perforationform to improve the uniformity of the slurry distribution. Inparticular, the polishing pad is composed of two shaped layers, whereinthe upper layer is harder than the lower layer. During a polishingprocess, the harder upper layer provides a better flatness, while thesofter lower layer serving as a buffer layer providing a betteruniformity.

In the present invention, the strips can be replaced by dots. That is,the dots are buried in the mold and then the polymer foam material isinjected into the mold cavity of the mold. The polymer foam material iscured and molded. Thereafter, a mold release process is performed toobtain a molding polymer article. The dots in the molding article areremoved from the molding polymer article to form a polishing pad havingdot shaped cavities thereon.

In the method of manufacturing polishing pad of this invention, thestrips having various shapes, which are made of a polymer material or ametal, are buried in the mold and then the polymer foam material isinjected in the mold cavity of the mold. After the polymer foam materialis cured and molded, the strips are removed by applying an externalforce while removing of the skin of the molded polymer foam material.Therefore, a polishing pad having grooves is formed.

The polishing pad having grooves is formed by the above-mentionedmethod, so its fabrication is simpler than that of the prior art.

In the prevent invention, the pattern of the grooves of the polishingpad is not designed on the mold and the depth and the shape of thegrooves are dependant on the size and the shape of the strips.Therefore, the depth and the shape of the grooves vary easily accordingto the demand.

In the prevent invention, the grooves of the polishing pad are formed byburying and removal the strips in the mold, so that the pattern of thegrooves comprise various complex patterns, which can not be produced bya blade.

In the prior art, since the sharp and the linear velocity of the blade,and the temperature and the humidity of the atmosphere are not fixed,the number of the macro defects formed on the polishing pad aredifferent, and the performance of each polishing pad has a largedifference. However, in the present invention, the grooves are notformed by a cutting means, and the drawbacks of the difference in thenumber of the macro defects on the polishing pad can be prevented.Therefore, the performance of each polishing pad is more uniform.

In the present invention, since the grooves of the polishing pad are notformed by a cutting means, there is not debris produced. Therefore, avacuum cleaner is not necessary in this invention.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a flow chart of manufacturing apolishing pad with a single-layered structure according to a firstpreferred embodiment of the present invention.

FIG. 2 schematically illustrates a flow chart of manufacturing apolishing pad with a two-layered structure according to a secondpreferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIG. 1 schematically illustrates a flow chart of manufacturing apolishing pad with a single-layered structure according to the firstpreferred embodiment of the present invention.

Referring to FIG. 1, a mold having a mold cavity therein is provided(step 100). The size of the mold cavity is suitable for forming adesired polishing pad. Thereafter, strips are previously buried in themold (step 102). A cross-sectional shape of the strips comprises apolygon form, an arc form or an irregular form; for example, atriangular shape, a hexagon shape, a circular shape, a square shape, arectangular shape, a spiral shape, a tree-form or a radiative form, etc.Those strips are arranged to form a radiative form, a concentric circleform, a grid form, a triangle form, a spiral form, a rhombus form or aperforation form. In this embodiment, materials of the strips comprise apolymer material or a metal material, wherein the polymer material canbe polypropylene, polyethylene or polytetrafluoroethylene, for example.

After the strips have been buried in the mold cavity of the mold, apolymer foam material, such as a polyurea foam material, is injectedinto the mold cavity of the mold by a reaction injection molding means.Afterwards, the polymer foam material is cured to mold the polymer foammaterial into a molding polymer article (step 104). A mold releaseprocess is performed to obtain the molding polymer article (step 106).Thereafter, the strips on the molding article are removed to form apolishing pad having at least one groove thereon (step 108). The stripsare removed from the molding article by a scraping method or by applyingan external force to draw out the strips.

The pattern of the grooves on the polishing pad is transferred from thestrips buried in the mold cavity of the mold, so that the pattern of thegrooves comprises a radiative form, a concentric circle form, a gridform, a triangle form, a spiral form, a rhombus form or a perforationform. In addition, in this embodiment, a width of the grooves is about0.5 to 15 mm, a depth of the grooves is about 0.2 to 2.5 mm, and a pitchof the grooves is about 0.2 to 20 mm.

It should be noted that the strips comprise a decomposable material or awater-soluble polymer material. Consequently, after the mold releaseprocess is performed and the molding article is obtained (step 106), adecomposed process or a hydrolysis process can be performed to removethe strips on the molding article and then the polishing pad havinggrooves is obtained.

Second Embodiment

FIG. 2 schematically illustrates a flow chart of manufacturing apolishing pad with a two-layered structure according to the secondpreferred embodiment of the present invention. Referring to FIG. 2, amold having a mold cavity is provided (step 200). The size of the moldcavity is suitable for forming a desired polishing pad. Thereafter,strips are buried in the mold (step 202). A cross-sectional shape of thestrips comprises a polygon form, an arc form or an irregular form; forexample, a triangular shape, a hexagon shape, a circular shape, a squareshape, a rectangular shape, a spiral shape, a tree-form or a radiativeform. Those strips are arranged to form a radiative form, a concentriccircle form, a grid form, a triangle form, a spiral form, a rhombus formor a perforation form. In this embodiment, the material of the stripscomprises a polymer material or a metal material, wherein the polymermaterial can be polypropylene, polyethylene or polytetrafluoroethylene,for example.

After the strips are buried in the mold cavity of the mold, a firstpolymer foam material, such as a polyurea foam material, is injectedinto and partially fill the mold cavity of the mold by a reactioninjection molding means. Afterwards, the first polymer foam material iscured to mold the first polymer foam material into a first shaped layer(step 204). Thereafter, a second polymer material is injected into theremaining space of the mold cavity of the mold, wherein the secondpolymer material comprises polyurea material, a silicone rubber,polybutadiene rubber, poly (vinyl chloride) latex or poly (methylmethacrylate) latex. Afterwards, the second polymer material is cured tomold the polymer material into a second shaped layer (step 206).

A mold release process is performed to obtain a molding polymer articlehaving two shaped layers (step 208), wherein the hardness of the firstshaped layer is higher than that of the second shaped layer. In thisembodiment, the hardness of the first shaped layer is 30 to 80 shore D,and the hardness of the second shaped layer is 5 to 60 shore A. During apolishing process, the harder first shaped layer provides a betterflatness, while the softer second shaped layer serving as a buffer layerprovides a better uniformity.

Thereafter, the strips on the molding article are removed to form apolishing pad having grooves thereon (step 210). The strips are removedfrom the molding article by a scraping method or by applying an externalforce to draw out the strips.

The pattern of the grooves on the polishing pad is transferred from thestrips buried in the mold cavity of the mold, so that the pattern of thegrooves comprises a radiative form, a concentric circle form, a gridform, a triangle form, a spiral form, a rhombus form or a perforationform. Additionally, in this embodiment, a width of the grooves is about0.5 to 15 mm, a depth of the grooves is about 0.2 to 2.5 mm, and a pitchof the grooves is about 0.2 to 20 mm.

It should be noted that the strips comprise a decomposable material or awater-soluble polymer material. Consequently, after the mold releaseprocess is performed and the molding article is obtained (step 208), adecomposed process or a hydrolysis process can be performed to removethe strips on the molding article and then the polishing pad havinggrooves thereon is obtained.

In the present invention, the strips can be replaced by dots. That is,the dots are previously buried in the mold and then the polymer foammaterial is injected into the mold cavity of the mold. The polymer foammaterial is cured and molded. Thereafter, a mold release process isperformed to obtain a molding polymer article. The dots in the moldingarticle are removed from the molding polymer article to form a polishingpad having dot shaped cavities thereon.

The method of manufacturing the polishing pad of this invention is thatthe strips having various shapes are previously buried in the mold andthen the polymer foam material is injected into the mold cavity of themold. After the polymer foam material is cured and molded, the stripsare removed by applying an external force during the removal of the skinof the molded polymer foam material. The polishing pad of this inventionis not formed by performing a cutting means on a pad by a blade to formgrooves thereon as the prior art. Therefore, the fabrication of thisinvention is simpler than the prior art method. The depth and the shapeof the grooves can be easily varied according to the demand and thepattern of the grooves comprises various complex patterns, which cannotbe formed by the cutting means of a blade. In addition, the problem ofthe macro defects formed on the polishing pad can be prevented, andtherefore the performance of each polishing pad of this invention has ahigher uniformity. Moreover, there is no debris produced in themanufacturing process, so that a vacuum cleaner is not necessary in thisinvention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncovers modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A method of manufacturing a polishing pad, comprising: providing amold having a mold cavity therein; burying a water-soluble material inthe mold, wherein a configuration of the water-soluble materialcomprises at least one strip or at least one dot; injecting a polymermaterial into the mold cavity of the mold; curing the polymer materialto mold the polymer material into a molding article; performing a moldrelease process to obtain the molding article; and making thewater-soluble material hydrolyze to form a polishing pad having at leastone groove or at least one dot shaped cavity thereon.
 2. The method ofmanufacturing a polishing pad of claim 1, wherein a cross-sectionalshape of the water-soluble material comprises a polygon form, an arcform or an irregular form.
 3. The method of manufacturing a polishingpad of claim 1, wherein a cross-sectional shape of the water-solublematerial comprises a triangular shape, a hexagon shape, a circularshape, a square shape, a rectangular shape, a spiral shape, a tree-formor a radiative form.
 4. The method of manufacturing a polishing pad ofclaim 1, wherein a pattern of the water-soluble material comprises aradiative form, a concentric circle form, a grid form, a triangle form,a spiral form, a rhombus form or a perforation form.
 5. The method ofmanufacturing a polishing pad of claim 1, wherein the polymer materialcomprises a polyurea foam material.
 6. The method of manufacturing apolishing pad of claim 1, wherein a width of the at least one groove orthe at least one dot shaped cavity is 0.5 to 15 mm, a depth of the atleast one groove or the at least one dot shaped cavity is 0.2 to 2.5 mm,and a pitch of the at least one groove or the at least one dot shapedcavity is 0.2 to 20 mm.
 7. A method of manufacturing a polishing pad,comprising: providing a mold having a mold cavity therein; burying adecomposable material in the mold, wherein a configuration of thedecomposable material comprises at least one strip or at least one dot;injecting a polymer material into the mold cavity of the mold; curingthe polymer material to mold the polymer material into a moldingarticle; performing a mold release process to obtain the moldingarticle; and making the decomposable material decompose to form apolishing pad having at least one groove or at least one dot shapedcavity thereon.
 8. The method of manufacturing a polishing pad of claim7, wherein a cross-sectional shape of the decomposable materialcomprises a polygon form, an arc form or an irregular form.
 9. Themethod of manufacturing a polishing pad of claim 7, wherein across-sectional shape of the decomposable material comprises atriangular shape, a hexagon shape, a circular shape, a square shape, arectangular shape, a spiral shape, a tree-form or a radiative form. 10.The method of manufacturing a polishing pad of claim 7, wherein amaterial of the decomposable material comprises a water-soluble polymermaterial.
 11. The method of manufacturing a polishing pad of claim 7,wherein a pattern of the decomposable material comprises a radiativeform, a concentric circle form, a grid form, a triangle form, a spiralform, a rhombus form or a perforation form.
 12. The method ofmanufacturing a polishing pad of claim 7, wherein the polymer materialcomprises a polyurea foam material.
 13. The method of manufacturing apolishing pad of claim 7, wherein a width of the at least one groove orthe at least one dot shaped cavity is 0.5 to 15 mm, a depth of the atleast one groove or the at least one dot shaped cavity is 0.2 to 2.5 mm,and a pitch of the at least one groove or the at least one dot shapedcavity is 0.2 to 20 mm.
 14. A method of manufacturing a polishing pad,comprising: providing a mold having a mold cavity therein; burying atleast one strip or at least one dot in the mold; injecting a firstpolymer material partially filling into the mold cavity of the mold;curing the first polymer material to mold the first polymer material forforming a first shaped layer; injecting a second polymer material intothe remaining spacing of the mold cavity of the mold; curing the secondpolymer material to mold the second polymer material for forming asecond shaped layer; performing a mold release process to obtain amolding article having the first and the second shaped layers; andremoving the strip or the dot from the molding article to form apolishing pad having at least one groove or at least one dot shapedcavity thereon.
 15. The method of manufacturing a polishing pad of claim14, wherein a hardness of the first shaped layer is higher than that ofthe second shaped layer.
 16. The method of manufacturing a polishing padof claim 15, wherein the hardness of the first shaped layer is 30 to 80shore D, and the hardness of the second shaped layer is 5 to 60 shore A.17. The method of manufacturing a polishing pad of claim 15, wherein thefirst shaped layer is an upper layer and the second shaped layer is alower layer of the polishing pad.
 18. The method of manufacturing apolishing pad of claim 14, wherein the first polymer material comprisesa polyurea foam material.
 19. The method of manufacturing polishing padof claim 14, wherein the second polymer material comprises a polyureamaterial, a silicone rubber, polybutadiene rubber, poly (vinyl chloride)latex or poly (methyl methacrylate) latex.
 20. The method ofmanufacturing polishing pad of claim 14, wherein a cross-sectional shapeof the strip or the dot comprises a polygon form, an arc form or anirregular form.
 21. The method of manufacturing a polishing pad of claim14, wherein a cross-sectional shape of the strip or the dot comprises atriangular shape, a hexagon shape, a circular shape, a square shape, arectangular shape, a spiral shape, a tree-form or a radiative form. 22.The method of manufacturing a polishing pad of claim 14, wherein amaterial of the at least one strip or the at least one dot comprises athird polymer material or a metal material.
 23. The method ofmanufacturing a polishing pad of claim 22, wherein the third polymermaterial comprises polypropylene, polyethylene orpolytetrafluoroethylene.
 24. The method of the manufacturing a polishingpad of claim 14, wherein the step of removing the strip or the dot fromthe molding article is performed by a scraping method or by applying aexternal force to draw out the strip or the dot.
 25. The method of themanufacturing a polishing pad of claim 14, wherein a material of thestrip or the dot comprises a decomposable material or a water-solublepolymer material.
 26. The method of the manufacturing a polishing pad ofclaim 25, wherein the step of removing the strip or the dot from themolding article is performed by a decomposing process or a hydrolysisprocess.
 27. The method of manufacturing a polishing pad of claim 14,wherein a pattern of the at least one groove or the at least one dotcomprises a radiative form, a concentric circle form, a grid form, atriangle form, a spiral form, a rhombus form or a perforation form. 28.The method of the manufacturing a polishing pad of claim 14, wherein awidth of the at least one groove or the at least one dot is 0.5 to 15mm, a depth of the at least one groove or the at least one dot is 0.2 to2.5 mm, and a pitch of the at least one groove or the at least one dotis 0.2 to 20 mm.